In a conventional chain arrangement for conveying articles, an elongated endless metal chain extends between horizontally spaced sprocket wheels, at least one of which is rotatably driven, and the top or upper reach of the chain defines a conveying surface for articles. The conventional metal chain is typically formed from metal links (FIGS. 1A and 1B) having integral top plates T on which articles are placed, which top plates terminate in hinge parts H for receiving therein pins P for hingedly connecting the top plates T together. This known link typically has a configuration which, when viewed from the end of the link, appears substantially as illustrated in FIG. 2A, in that the top plate T extends substantially tangentially between the hinge parts H defined on the opposite edges thereof, which hinge parts are formed as a curled or wound open portion substantially integral with and at the end of the top plate. However, during usage, it has been observed that the links undergo a change in configuration from that illustrated in FIG. 2A to that illustrated in FIG. 2B. This change in the link, as illustrated in FIG. 2B, is believed due to the severe tension imposed on the chain as a result of the load of the articles being conveyed thereon, and/or due to the fatiguing of the links. In this changed state illustrated by FIG. 2B, the upper conveying surface defined by the top plate T is hence deformed, and this results in substantial instability due to the inability of the articles positioned on the chain to make intimate supportive contact with the outer surface of the top plates. This can hence make conveying of the articles more difficult, and under some circumstances can be damaging to the articles.
The conventional chain illustrated by the link of FIG. 2A, particularly when deformed as illustrated by FIG. 2B, is also disadvantageous in that it is not possible to easily replace the deformed or worn top plate since it is integral with the link, and therefore the whole chain has to be replaced or disassembled to permit replacement of selected links. Further, since the whole chain is made up of metal links, the chain is heavy and thus a large driving force is required for the chain, and the metal chain also generates substantial noise which substantially undesirably affects the operating environment. Further, in those metal chains in which a floating preventive guide plate is required, the providing of such guide plate on the metal links is a troublesome manufacturing step inasmuch as such guide plates normally must be welded onto the lower surface of the top plate.
Accordingly, an object of the present invention is to overcome the above disadvantages by providing an improved hinge-type table top chain in which the articles can be conveyed in a stabilized manner without being damaged, the chain can be of light weight to minimize the required driving force, the generation of noises by the chain is substantially minimized, the top plate can be easily and individually removed from its respective chain link to permit replacement thereof without requiring disassembly of the chain, and the top plate can be easily and inexpensively molded from a plastics material and can have the guide plate integrally molded therewith if desired.
In the hinge-type table top chain arrangement of this invention, an endless base chain is formed from a plurality of hingedly connected metal link plates. A top plate is removably attached to the center portion of and effectively overlies each of the link plates, which top plate is preferably molded from a plastics material and defines an outer substantially planar surface for supportive engagement with articles to be conveyed. The top plates have end edges which, in the longitudinal direction of the chain, are disposed in close proximity to similar end edges as associated with top plates mounted on adjacent hingedly joined link plates.
Other objects and purposes of the invention will be apparent to persons familiar with chain arrangements of this general type upon reading the following specification and inspecting the accompanying drawings.